1. Field of the Invention
The object of the present invention is a method for providing optimum heat exchange within an assembly consisting of a heat-conducting absorbing plate and a heat transfer fluid flowing in at least one heat-conducting tubular conduit. It is notably, but not exclusively, applied to collectors of solar heat panels.
2. Description of the Prior Art
It is known that collectors of solar heat panels comprise:                a plate, generally in copper or in aluminum, the upper face of which is coated with a selective layer promoting absorption of solar light;        tubing having a circular shaped section which is welded on the lower face of said plate, this tubing generally being in copper or in aluminum;        a heat transfer liquid flowing in the tubing.        
In this way, solar light incident on the upper face of said plate is converted into heat, the latter being conducted towards the welding area and then to the walls of the tubing so as to be transmitted to the heat transfer liquid which heats up while it passes in said tubing.
This device nevertheless has the following drawbacks:                transmission of heat from the wall of a tubing towards the heat transfer liquid is optimum when the temperature difference between said wall and the heat transfer liquid is large or, in the vicinity of the wall, the temperature of the heat transfer liquid is close to that of this wall;        as the heat transfer liquid is not as good a heat conductor as copper, transmission of the heat of the liquid located in the vicinity of the wall of a tubing towards the centre of the liquid is not optimum.        
Thus, the flow of the heat transfer fluid in the tubing is laminar and the temperature distribution is not uniform, indeed, the temperature of the heat transfer liquid decreases from the upper layers located in proximity to the wall of a tube towards the centre of the liquid, consequently, the heat exchanges within the heat transfer liquid and between the tubing and the heat transfer liquid are not optimum.